Skip to main content

Main menu

  • Home
  • Articles
    • Current
    • Archive
    • Supplemental Issues
    • Collections - French
    • Collections - English
  • Info for
    • Authors & Reviewers
    • Submit a Manuscript
    • Advertisers
    • Careers & Locums
    • Subscribers
    • Permissions
  • About CFP
    • About CFP
    • About the CFPC
    • Editorial Advisory Board
    • Terms of Use
    • Contact Us
  • Feedback
    • Feedback
    • Rapid Responses
    • Most Read
    • Most Cited
    • Email Alerts
  • Blogs
    • Latest Blogs
    • Blog Guidelines
    • Directives pour les blogues
  • Mainpro+ Credits
    • About CFP Mainpro+
    • Member Login
    • Instructions
  • Other Publications
    • http://www.cfpc.ca/Canadianfamilyphysician/
    • https://www.cfpc.ca/Login/
    • Careers and Locums

User menu

  • My alerts

Search

  • Advanced search
The College of Family Physicians of Canada
  • Other Publications
    • http://www.cfpc.ca/Canadianfamilyphysician/
    • https://www.cfpc.ca/Login/
    • Careers and Locums
  • My alerts
The College of Family Physicians of Canada

Advanced Search

  • Home
  • Articles
    • Current
    • Archive
    • Supplemental Issues
    • Collections - French
    • Collections - English
  • Info for
    • Authors & Reviewers
    • Submit a Manuscript
    • Advertisers
    • Careers & Locums
    • Subscribers
    • Permissions
  • About CFP
    • About CFP
    • About the CFPC
    • Editorial Advisory Board
    • Terms of Use
    • Contact Us
  • Feedback
    • Feedback
    • Rapid Responses
    • Most Read
    • Most Cited
    • Email Alerts
  • Blogs
    • Latest Blogs
    • Blog Guidelines
    • Directives pour les blogues
  • Mainpro+ Credits
    • About CFP Mainpro+
    • Member Login
    • Instructions
  • RSS feeds
  • Follow cfp Template on Twitter
OtherPractice

From beer brewing to vaccine stability

Adding a digital temperature controller to your vaccine refrigerator

Peter Hutten-Czapski
Canadian Family Physician July 2017, 63 (7) 544-545;
Peter Hutten-Czapski
Practising rural physician in Haileybury, Ont.
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • Article
  • Figures & Data
  • eLetters
  • Info & Metrics
  • PDF
Loading

Your practice nurse walks by with a cooler full of vaccines that she is returning to public health. “The refrigerator’s temperature went out of range last night ... again.” You adjust the temperature on the refrigerator but the thermostat just does not allow for fine enough adjustments.

Stability data demonstrate that freezing (< 0°C) most refrigerated vaccines destroys them.1 Additionally, while all vaccines cumulatively lose potency with time, the loss in potency is accelerated in a vaccine-specific manner when they are stored above the recommended temperature.1 Thus, frozen vaccine is usually discarded, and vaccines that have been exposed to temperatures above recommended ranges should be marked and, depending on the particular preparation and the extent of exposure, used before other stock.

For these reasons suppliers use purpose-built vaccine refrigerators to keep stock between 2°C and 8°C. Some pharmaceutical-grade refrigerators2 have features such as digital temperature control, forced air circulation, and alarms, with a rated temperature stability of ± 1°C. Such refrigerators, however, are expensive.

Home beer makers also have strict temperature requirements for their products. After watching a YouTube video on how to wire a digital temperature controller added to a domestic refrigerator for brewing use,3 it seemed reasonable to add a digital temperature controller to a refrigerator used for vaccine storage.

Materials

The following materials are needed:

  • 4-ft3 cooler-only refrigerator (about $200);

  • 3/16-inch flat screwdriver;

  • 14-gauge power cable;

  • STC-1000 digital temperature controller (purchased online for about $20);

  • plastic or metal enclosure (about $8);

  • drill and file;

  • wire strippers;

  • soldering iron and tin; and

  • digital maximum-minimum thermometer (about $20) to measure vaccine temperature with the probe submerged in a vial of glycol, as indicated by the Centers for Disease Control and Prevention.4

Considerations

Put your refrigerator on bypass.

Using the temperature controller as a bypass requires setting up the controller to intermittently power an electrical plug for a domestic refrigerator when the air probe temperature is higher than the set point. The refrigerator in turn is set to run at its coldest setting and is plugged into the controlled plug.

We took an enclosure (in this case a recycled computer power supply), gutted its original contents, and cut a rectangular hole to receive the controller. Then wiring was attached to the controller from the incoming power cord to a switched plug (Figures 1 and 2).

Figure 1.
  • Download figure
  • Open in new tab
Figure 1.

The wiring of a bypass temperature controller

Figure 2.
  • Download figure
  • Open in new tab
Figure 2.

Schematic and pinout of a bypass temperature controller

The calibration of the temperature probes was tested against ice water as a reference.

The digital thermometer probe was run past the gasket at the top of the refrigerator door and placed in the centre of the refrigerator measuring the air temperature. The finished assembled bypass is shown in Figure 3.

Figure 3.
  • Download figure
  • Open in new tab
Figure 3.

Assembled bypass controller

Optional improvements.

We put a standard 12-volt computer case fan (about $20) inside the refrigerator to reduce temperature variation. We found that the variation between the bottom and top of the refrigerator decreased from 5°C to 2.5°C with fan operation at a cost of wider temperature swings with door-opening events.

We use water bottles in nonusable high- and low-temperature areas of the refrigerator (crisper, door, and top and bottom shelves) to add thermal ballast. The water bottles displace 10% of the rated refrigerator volume and slow internal heating to 0.04°C/min when the refrigerator turns off owing to power failures; this extends the time that the refrigerator keeps vaccines under 8°C during power failures to more than an hour (about $4 for 10 L of water bottles).

Clinic’s experience with the technique and settings.

We keep our temperature controller set to 3.8°C (air) with cooling cycling after a 1°C change. Over a month’s time, this kept the vaccine thermometer between 3.5°C and 7.2°C. (With the refrigerator’s original mechanical thermostat, the previous month’s vial temperature ranged between 2.4°C and 7.7°C.)

We had not experienced any cold-chain failures from the time of installation of the digital temperature controller to the time of manuscript submission to Canadian Family Physician.

Conclusion

Adding a digital thermometer controller to your refrigerator is a practical approach to controlling temperature variations in domestic refrigerators, potentially to the level of pharmaceutical-grade tolerances. Those who are uncomfortable with their wiring skills can consider prewired digital bypass controllers that are available (about $170).

Acknowledgments

I thank Dr David Page for his input throughout the study and for reviewing the manuscript draft.

Notes

We encourage readers to share some of their practice experience: the neat little tricks that solve difficult clinical situations. Praxis articles can be submitted online at http://mc.manuscriptcentral.com/cfp or through the CFP website (www.cfp.ca) under “Authors and Reviewers.”

Footnotes

  • Competing interests

    None declared

  • Copyright© the College of Family Physicians of Canada

References

  1. 1.↵
    1. World Health Organization
    . Temperature sensitivity of vaccines. Geneva, Switz: World Health Organization; 2006. Available from: http://apps.who.int/iris/bitstream/10665/69387/1/WHO_IVB_06.10_eng.pdf. Accessed 2017 May 8.
  2. 2.↵
    1. 360 Medical [website]
    . Products: 2∼8°C pharmacy refrigerators, model: HYC-610 2015. Schomberg, ON: 360 Medical; Available from: http://360medical.ca/pharmacy-refrigerators-HYC-610.html. Accessed 2017 May 8.
  3. 3.↵
    How to wire the STC 1000 temperature controller [video]. YouTube; 2012. Available from: www.youtube.com/watch?v=30TvX1Zz1-Y. Accessed 2017 May 8.
  4. 4.↵
    1. Beckenhaupt P
    . Guidelines for storage and temperature monitoring of refrigerated vaccines. Atlanta, GA: Centers for Disease Control and Prevention; 2012. Available from: www.cdc.gov/vaccines/hcp/admin/storage/toolkit/toolkit-resources.pdf. Accessed 2017 May 8.
PreviousNext
Back to top

In this issue

Canadian Family Physician: 63 (7)
Canadian Family Physician
Vol. 63, Issue 7
1 Jul 2017
  • Table of Contents
  • About the Cover
  • Index by author
Print
Download PDF
Article Alerts
Sign In to Email Alerts with your Email Address
Email Article

Thank you for your interest in spreading the word on The College of Family Physicians of Canada.

NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.

Enter multiple addresses on separate lines or separate them with commas.
From beer brewing to vaccine stability
(Your Name) has sent you a message from The College of Family Physicians of Canada
(Your Name) thought you would like to see the The College of Family Physicians of Canada web site.
Citation Tools
From beer brewing to vaccine stability
Peter Hutten-Czapski
Canadian Family Physician Jul 2017, 63 (7) 544-545;

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
Respond to this article
Share
From beer brewing to vaccine stability
Peter Hutten-Czapski
Canadian Family Physician Jul 2017, 63 (7) 544-545;
del.icio.us logo Digg logo Reddit logo Twitter logo CiteULike logo Facebook logo Google logo Mendeley logo
  • Tweet Widget
  • Facebook Like
  • Google Plus One

Jump to section

  • Article
    • Materials
    • Considerations
    • Conclusion
    • Acknowledgments
    • Notes
    • Footnotes
    • References
  • Figures & Data
  • Info & Metrics
  • eLetters
  • PDF

Related Articles

  • No related articles found.
  • Scopus
  • PubMed
  • Google Scholar

Cited By...

  • No citing articles found.
  • Scopus (1)
  • Google Scholar

More in this TOC Section

Practice

  • Measuring what really matters
  • Topical treatments for rosacea
  • Palliative care in patients with severe mental illness
Show more Practice

Praxis

  • Quick and painless
  • Managing hypertension in primary care
  • Prévention des allergies alimentaires par l’introduction précoce d’aliments
Show more Praxis

Similar Articles

Navigate

  • Home
  • Current Issue
  • Archive
  • Collections - English
  • Collections - Française

For Authors

  • Authors and Reviewers
  • Submit a Manuscript
  • Permissions
  • Terms of Use

General Information

  • About CFP
  • About the CFPC
  • Advertisers
  • Careers & Locums
  • Editorial Advisory Board
  • Subscribers

Journal Services

  • Email Alerts
  • Twitter
  • RSS Feeds

Copyright © 2019 by The College of Family Physicians of Canada

Powered by HighWire